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<a class="jxr_linenumber" name="1" href="#1">1</a>   <em class="jxr_comment">/*</em>
<a class="jxr_linenumber" name="2" href="#2">2</a>   <em class="jxr_comment"> * Copyright 2012 The Netty Project</em>
<a class="jxr_linenumber" name="3" href="#3">3</a>   <em class="jxr_comment"> *</em>
<a class="jxr_linenumber" name="4" href="#4">4</a>   <em class="jxr_comment"> * The Netty Project licenses this file to you under the Apache License,</em>
<a class="jxr_linenumber" name="5" href="#5">5</a>   <em class="jxr_comment"> * version 2.0 (the "License"); you may not use this file except in compliance</em>
<a class="jxr_linenumber" name="6" href="#6">6</a>   <em class="jxr_comment"> * with the License. You may obtain a copy of the License at:</em>
<a class="jxr_linenumber" name="7" href="#7">7</a>   <em class="jxr_comment"> *</em>
<a class="jxr_linenumber" name="8" href="#8">8</a>   <em class="jxr_comment"> *   <a href="http://www.apache.org/licenses/LICENSE-2.0" target="alexandria_uri">http://www.apache.org/licenses/LICENSE-2.0</a></em>
<a class="jxr_linenumber" name="9" href="#9">9</a>   <em class="jxr_comment"> *</em>
<a class="jxr_linenumber" name="10" href="#10">10</a>  <em class="jxr_comment"> * Unless required by applicable law or agreed to in writing, software</em>
<a class="jxr_linenumber" name="11" href="#11">11</a>  <em class="jxr_comment"> * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT</em>
<a class="jxr_linenumber" name="12" href="#12">12</a>  <em class="jxr_comment"> * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the</em>
<a class="jxr_linenumber" name="13" href="#13">13</a>  <em class="jxr_comment"> * License for the specific language governing permissions and limitations</em>
<a class="jxr_linenumber" name="14" href="#14">14</a>  <em class="jxr_comment"> * under the License.</em>
<a class="jxr_linenumber" name="15" href="#15">15</a>  <em class="jxr_comment"> */</em>
<a class="jxr_linenumber" name="16" href="#16">16</a>  <strong class="jxr_keyword">package</strong> org.jboss.netty.handler.codec.frame;
<a class="jxr_linenumber" name="17" href="#17">17</a>  
<a class="jxr_linenumber" name="18" href="#18">18</a>  <strong class="jxr_keyword">import</strong> org.jboss.netty.buffer.ChannelBuffer;
<a class="jxr_linenumber" name="19" href="#19">19</a>  <strong class="jxr_keyword">import</strong> org.jboss.netty.channel.Channel;
<a class="jxr_linenumber" name="20" href="#20">20</a>  <strong class="jxr_keyword">import</strong> org.jboss.netty.channel.ChannelHandlerContext;
<a class="jxr_linenumber" name="21" href="#21">21</a>  <strong class="jxr_keyword">import</strong> org.jboss.netty.channel.Channels;
<a class="jxr_linenumber" name="22" href="#22">22</a>  
<a class="jxr_linenumber" name="23" href="#23">23</a>  <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="24" href="#24">24</a>  <em class="jxr_javadoccomment"> * A decoder that splits the received {@link ChannelBuffer}s dynamically by the</em>
<a class="jxr_linenumber" name="25" href="#25">25</a>  <em class="jxr_javadoccomment"> * value of the length field in the message.  It is particularly useful when you</em>
<a class="jxr_linenumber" name="26" href="#26">26</a>  <em class="jxr_javadoccomment"> * decode a binary message which has an integer header field that represents the</em>
<a class="jxr_linenumber" name="27" href="#27">27</a>  <em class="jxr_javadoccomment"> * length of the message body or the whole message.</em>
<a class="jxr_linenumber" name="28" href="#28">28</a>  <em class="jxr_javadoccomment"> * &lt;p&gt;</em>
<a class="jxr_linenumber" name="29" href="#29">29</a>  <em class="jxr_javadoccomment"> * {@link LengthFieldBasedFrameDecoder} has many configuration parameters so</em>
<a class="jxr_linenumber" name="30" href="#30">30</a>  <em class="jxr_javadoccomment"> * that it can decode any message with a length field, which is often seen in</em>
<a class="jxr_linenumber" name="31" href="#31">31</a>  <em class="jxr_javadoccomment"> * proprietary client-server protocols. Here are some example that will give</em>
<a class="jxr_linenumber" name="32" href="#32">32</a>  <em class="jxr_javadoccomment"> * you the basic idea on which option does what.</em>
<a class="jxr_linenumber" name="33" href="#33">33</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="34" href="#34">34</a>  <em class="jxr_javadoccomment"> * &lt;h3&gt;2 bytes length field at offset 0, do not strip header&lt;/h3&gt;</em>
<a class="jxr_linenumber" name="35" href="#35">35</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="36" href="#36">36</a>  <em class="jxr_javadoccomment"> * The value of the length field in this example is &lt;tt&gt;12 (0x0C)&lt;/tt&gt; which</em>
<a class="jxr_linenumber" name="37" href="#37">37</a>  <em class="jxr_javadoccomment"> * represents the length of "HELLO, WORLD".  By default, the decoder assumes</em>
<a class="jxr_linenumber" name="38" href="#38">38</a>  <em class="jxr_javadoccomment"> * that the length field represents the number of the bytes that follows the</em>
<a class="jxr_linenumber" name="39" href="#39">39</a>  <em class="jxr_javadoccomment"> * length field.  Therefore, it can be decoded with the simplistic parameter</em>
<a class="jxr_linenumber" name="40" href="#40">40</a>  <em class="jxr_javadoccomment"> * combination.</em>
<a class="jxr_linenumber" name="41" href="#41">41</a>  <em class="jxr_javadoccomment"> * &lt;pre&gt;</em>
<a class="jxr_linenumber" name="42" href="#42">42</a>  <em class="jxr_javadoccomment"> * &lt;b&gt;lengthFieldOffset&lt;/b&gt;   = &lt;b&gt;0&lt;/b&gt;</em>
<a class="jxr_linenumber" name="43" href="#43">43</a>  <em class="jxr_javadoccomment"> * &lt;b&gt;lengthFieldLength&lt;/b&gt;   = &lt;b&gt;2&lt;/b&gt;</em>
<a class="jxr_linenumber" name="44" href="#44">44</a>  <em class="jxr_javadoccomment"> * lengthAdjustment    = 0</em>
<a class="jxr_linenumber" name="45" href="#45">45</a>  <em class="jxr_javadoccomment"> * initialBytesToStrip = 0 (= do not strip header)</em>
<a class="jxr_linenumber" name="46" href="#46">46</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="47" href="#47">47</a>  <em class="jxr_javadoccomment"> * BEFORE DECODE (14 bytes)         AFTER DECODE (14 bytes)</em>
<a class="jxr_linenumber" name="48" href="#48">48</a>  <em class="jxr_javadoccomment"> * +--------+----------------+      +--------+----------------+</em>
<a class="jxr_linenumber" name="49" href="#49">49</a>  <em class="jxr_javadoccomment"> * | Length | Actual Content |-----&gt;| Length | Actual Content |</em>
<a class="jxr_linenumber" name="50" href="#50">50</a>  <em class="jxr_javadoccomment"> * | 0x000C | "HELLO, WORLD" |      | 0x000C | "HELLO, WORLD" |</em>
<a class="jxr_linenumber" name="51" href="#51">51</a>  <em class="jxr_javadoccomment"> * +--------+----------------+      +--------+----------------+</em>
<a class="jxr_linenumber" name="52" href="#52">52</a>  <em class="jxr_javadoccomment"> * &lt;/pre&gt;</em>
<a class="jxr_linenumber" name="53" href="#53">53</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="54" href="#54">54</a>  <em class="jxr_javadoccomment"> * &lt;h3&gt;2 bytes length field at offset 0, strip header&lt;/h3&gt;</em>
<a class="jxr_linenumber" name="55" href="#55">55</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="56" href="#56">56</a>  <em class="jxr_javadoccomment"> * Because we can get the length of the content by calling</em>
<a class="jxr_linenumber" name="57" href="#57">57</a>  <em class="jxr_javadoccomment"> * {@link ChannelBuffer#readableBytes()}, you might want to strip the length</em>
<a class="jxr_linenumber" name="58" href="#58">58</a>  <em class="jxr_javadoccomment"> * field by specifying &lt;tt&gt;initialBytesToStrip&lt;/tt&gt;.  In this example, we</em>
<a class="jxr_linenumber" name="59" href="#59">59</a>  <em class="jxr_javadoccomment"> * specified &lt;tt&gt;2&lt;/tt&gt;, that is same with the length of the length field, to</em>
<a class="jxr_linenumber" name="60" href="#60">60</a>  <em class="jxr_javadoccomment"> * strip the first two bytes.</em>
<a class="jxr_linenumber" name="61" href="#61">61</a>  <em class="jxr_javadoccomment"> * &lt;pre&gt;</em>
<a class="jxr_linenumber" name="62" href="#62">62</a>  <em class="jxr_javadoccomment"> * lengthFieldOffset   = 0</em>
<a class="jxr_linenumber" name="63" href="#63">63</a>  <em class="jxr_javadoccomment"> * lengthFieldLength   = 2</em>
<a class="jxr_linenumber" name="64" href="#64">64</a>  <em class="jxr_javadoccomment"> * lengthAdjustment    = 0</em>
<a class="jxr_linenumber" name="65" href="#65">65</a>  <em class="jxr_javadoccomment"> * &lt;b&gt;initialBytesToStrip&lt;/b&gt; = &lt;b&gt;2&lt;/b&gt; (= the length of the Length field)</em>
<a class="jxr_linenumber" name="66" href="#66">66</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="67" href="#67">67</a>  <em class="jxr_javadoccomment"> * BEFORE DECODE (14 bytes)         AFTER DECODE (12 bytes)</em>
<a class="jxr_linenumber" name="68" href="#68">68</a>  <em class="jxr_javadoccomment"> * +--------+----------------+      +----------------+</em>
<a class="jxr_linenumber" name="69" href="#69">69</a>  <em class="jxr_javadoccomment"> * | Length | Actual Content |-----&gt;| Actual Content |</em>
<a class="jxr_linenumber" name="70" href="#70">70</a>  <em class="jxr_javadoccomment"> * | 0x000C | "HELLO, WORLD" |      | "HELLO, WORLD" |</em>
<a class="jxr_linenumber" name="71" href="#71">71</a>  <em class="jxr_javadoccomment"> * +--------+----------------+      +----------------+</em>
<a class="jxr_linenumber" name="72" href="#72">72</a>  <em class="jxr_javadoccomment"> * &lt;/pre&gt;</em>
<a class="jxr_linenumber" name="73" href="#73">73</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="74" href="#74">74</a>  <em class="jxr_javadoccomment"> * &lt;h3&gt;2 bytes length field at offset 0, do not strip header, the length field</em>
<a class="jxr_linenumber" name="75" href="#75">75</a>  <em class="jxr_javadoccomment"> *     represents the length of the whole message&lt;/h3&gt;</em>
<a class="jxr_linenumber" name="76" href="#76">76</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="77" href="#77">77</a>  <em class="jxr_javadoccomment"> * In most cases, the length field represents the length of the message body</em>
<a class="jxr_linenumber" name="78" href="#78">78</a>  <em class="jxr_javadoccomment"> * only, as shown in the previous examples.  However, in some protocols, the</em>
<a class="jxr_linenumber" name="79" href="#79">79</a>  <em class="jxr_javadoccomment"> * length field represents the length of the whole message, including the</em>
<a class="jxr_linenumber" name="80" href="#80">80</a>  <em class="jxr_javadoccomment"> * message header.  In such a case, we specify a non-zero</em>
<a class="jxr_linenumber" name="81" href="#81">81</a>  <em class="jxr_javadoccomment"> * &lt;tt&gt;lengthAdjustment&lt;/tt&gt;.  Because the length value in this example message</em>
<a class="jxr_linenumber" name="82" href="#82">82</a>  <em class="jxr_javadoccomment"> * is always greater than the body length by &lt;tt&gt;2&lt;/tt&gt;, we specify &lt;tt&gt;-2&lt;/tt&gt;</em>
<a class="jxr_linenumber" name="83" href="#83">83</a>  <em class="jxr_javadoccomment"> * as &lt;tt&gt;lengthAdjustment&lt;/tt&gt; for compensation.</em>
<a class="jxr_linenumber" name="84" href="#84">84</a>  <em class="jxr_javadoccomment"> * &lt;pre&gt;</em>
<a class="jxr_linenumber" name="85" href="#85">85</a>  <em class="jxr_javadoccomment"> * lengthFieldOffset   =  0</em>
<a class="jxr_linenumber" name="86" href="#86">86</a>  <em class="jxr_javadoccomment"> * lengthFieldLength   =  2</em>
<a class="jxr_linenumber" name="87" href="#87">87</a>  <em class="jxr_javadoccomment"> * &lt;b&gt;lengthAdjustment&lt;/b&gt;    = &lt;b&gt;-2&lt;/b&gt; (= the length of the Length field)</em>
<a class="jxr_linenumber" name="88" href="#88">88</a>  <em class="jxr_javadoccomment"> * initialBytesToStrip =  0</em>
<a class="jxr_linenumber" name="89" href="#89">89</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="90" href="#90">90</a>  <em class="jxr_javadoccomment"> * BEFORE DECODE (14 bytes)         AFTER DECODE (14 bytes)</em>
<a class="jxr_linenumber" name="91" href="#91">91</a>  <em class="jxr_javadoccomment"> * +--------+----------------+      +--------+----------------+</em>
<a class="jxr_linenumber" name="92" href="#92">92</a>  <em class="jxr_javadoccomment"> * | Length | Actual Content |-----&gt;| Length | Actual Content |</em>
<a class="jxr_linenumber" name="93" href="#93">93</a>  <em class="jxr_javadoccomment"> * | 0x000E | "HELLO, WORLD" |      | 0x000E | "HELLO, WORLD" |</em>
<a class="jxr_linenumber" name="94" href="#94">94</a>  <em class="jxr_javadoccomment"> * +--------+----------------+      +--------+----------------+</em>
<a class="jxr_linenumber" name="95" href="#95">95</a>  <em class="jxr_javadoccomment"> * &lt;/pre&gt;</em>
<a class="jxr_linenumber" name="96" href="#96">96</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="97" href="#97">97</a>  <em class="jxr_javadoccomment"> * &lt;h3&gt;3 bytes length field at the end of 5 bytes header, do not strip header&lt;/h3&gt;</em>
<a class="jxr_linenumber" name="98" href="#98">98</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="99" href="#99">99</a>  <em class="jxr_javadoccomment"> * The following message is a simple variation of the first example.  An extra</em>
<a class="jxr_linenumber" name="100" href="#100">100</a> <em class="jxr_javadoccomment"> * header value is prepended to the message.  &lt;tt&gt;lengthAdjustment&lt;/tt&gt; is zero</em>
<a class="jxr_linenumber" name="101" href="#101">101</a> <em class="jxr_javadoccomment"> * again because the decoder always takes the length of the prepended data into</em>
<a class="jxr_linenumber" name="102" href="#102">102</a> <em class="jxr_javadoccomment"> * account during frame length calculation.</em>
<a class="jxr_linenumber" name="103" href="#103">103</a> <em class="jxr_javadoccomment"> * &lt;pre&gt;</em>
<a class="jxr_linenumber" name="104" href="#104">104</a> <em class="jxr_javadoccomment"> * &lt;b&gt;lengthFieldOffset&lt;/b&gt;   = &lt;b&gt;2&lt;/b&gt; (= the length of Header 1)</em>
<a class="jxr_linenumber" name="105" href="#105">105</a> <em class="jxr_javadoccomment"> * &lt;b&gt;lengthFieldLength&lt;/b&gt;   = &lt;b&gt;3&lt;/b&gt;</em>
<a class="jxr_linenumber" name="106" href="#106">106</a> <em class="jxr_javadoccomment"> * lengthAdjustment    = 0</em>
<a class="jxr_linenumber" name="107" href="#107">107</a> <em class="jxr_javadoccomment"> * initialBytesToStrip = 0</em>
<a class="jxr_linenumber" name="108" href="#108">108</a> <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="109" href="#109">109</a> <em class="jxr_javadoccomment"> * BEFORE DECODE (17 bytes)                      AFTER DECODE (17 bytes)</em>
<a class="jxr_linenumber" name="110" href="#110">110</a> <em class="jxr_javadoccomment"> * +----------+----------+----------------+      +----------+----------+----------------+</em>
<a class="jxr_linenumber" name="111" href="#111">111</a> <em class="jxr_javadoccomment"> * | Header 1 |  Length  | Actual Content |-----&gt;| Header 1 |  Length  | Actual Content |</em>
<a class="jxr_linenumber" name="112" href="#112">112</a> <em class="jxr_javadoccomment"> * |  0xCAFE  | 0x00000C | "HELLO, WORLD" |      |  0xCAFE  | 0x00000C | "HELLO, WORLD" |</em>
<a class="jxr_linenumber" name="113" href="#113">113</a> <em class="jxr_javadoccomment"> * +----------+----------+----------------+      +----------+----------+----------------+</em>
<a class="jxr_linenumber" name="114" href="#114">114</a> <em class="jxr_javadoccomment"> * &lt;/pre&gt;</em>
<a class="jxr_linenumber" name="115" href="#115">115</a> <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="116" href="#116">116</a> <em class="jxr_javadoccomment"> * &lt;h3&gt;3 bytes length field at the beginning of 5 bytes header, do not strip header&lt;/h3&gt;</em>
<a class="jxr_linenumber" name="117" href="#117">117</a> <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="118" href="#118">118</a> <em class="jxr_javadoccomment"> * This is an advanced example that shows the case where there is an extra</em>
<a class="jxr_linenumber" name="119" href="#119">119</a> <em class="jxr_javadoccomment"> * header between the length field and the message body.  You have to specify a</em>
<a class="jxr_linenumber" name="120" href="#120">120</a> <em class="jxr_javadoccomment"> * positive &lt;tt&gt;lengthAdjustment&lt;/tt&gt; so that the decoder counts the extra</em>
<a class="jxr_linenumber" name="121" href="#121">121</a> <em class="jxr_javadoccomment"> * header into the frame length calculation.</em>
<a class="jxr_linenumber" name="122" href="#122">122</a> <em class="jxr_javadoccomment"> * &lt;pre&gt;</em>
<a class="jxr_linenumber" name="123" href="#123">123</a> <em class="jxr_javadoccomment"> * lengthFieldOffset   = 0</em>
<a class="jxr_linenumber" name="124" href="#124">124</a> <em class="jxr_javadoccomment"> * lengthFieldLength   = 3</em>
<a class="jxr_linenumber" name="125" href="#125">125</a> <em class="jxr_javadoccomment"> * &lt;b&gt;lengthAdjustment&lt;/b&gt;    = &lt;b&gt;2&lt;/b&gt; (= the length of Header 1)</em>
<a class="jxr_linenumber" name="126" href="#126">126</a> <em class="jxr_javadoccomment"> * initialBytesToStrip = 0</em>
<a class="jxr_linenumber" name="127" href="#127">127</a> <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="128" href="#128">128</a> <em class="jxr_javadoccomment"> * BEFORE DECODE (17 bytes)                      AFTER DECODE (17 bytes)</em>
<a class="jxr_linenumber" name="129" href="#129">129</a> <em class="jxr_javadoccomment"> * +----------+----------+----------------+      +----------+----------+----------------+</em>
<a class="jxr_linenumber" name="130" href="#130">130</a> <em class="jxr_javadoccomment"> * |  Length  | Header 1 | Actual Content |-----&gt;|  Length  | Header 1 | Actual Content |</em>
<a class="jxr_linenumber" name="131" href="#131">131</a> <em class="jxr_javadoccomment"> * | 0x00000C |  0xCAFE  | "HELLO, WORLD" |      | 0x00000C |  0xCAFE  | "HELLO, WORLD" |</em>
<a class="jxr_linenumber" name="132" href="#132">132</a> <em class="jxr_javadoccomment"> * +----------+----------+----------------+      +----------+----------+----------------+</em>
<a class="jxr_linenumber" name="133" href="#133">133</a> <em class="jxr_javadoccomment"> * &lt;/pre&gt;</em>
<a class="jxr_linenumber" name="134" href="#134">134</a> <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="135" href="#135">135</a> <em class="jxr_javadoccomment"> * &lt;h3&gt;2 bytes length field at offset 1 in the middle of 4 bytes header,</em>
<a class="jxr_linenumber" name="136" href="#136">136</a> <em class="jxr_javadoccomment"> *     strip the first header field and the length field&lt;/h3&gt;</em>
<a class="jxr_linenumber" name="137" href="#137">137</a> <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="138" href="#138">138</a> <em class="jxr_javadoccomment"> * This is a combination of all the examples above.  There are the prepended</em>
<a class="jxr_linenumber" name="139" href="#139">139</a> <em class="jxr_javadoccomment"> * header before the length field and the extra header after the length field.</em>
<a class="jxr_linenumber" name="140" href="#140">140</a> <em class="jxr_javadoccomment"> * The prepended header affects the &lt;tt&gt;lengthFieldOffset&lt;/tt&gt; and the extra</em>
<a class="jxr_linenumber" name="141" href="#141">141</a> <em class="jxr_javadoccomment"> * header affects the &lt;tt&gt;lengthAdjustment&lt;/tt&gt;.  We also specified a non-zero</em>
<a class="jxr_linenumber" name="142" href="#142">142</a> <em class="jxr_javadoccomment"> * &lt;tt&gt;initialBytesToStrip&lt;/tt&gt; to strip the length field and the prepended</em>
<a class="jxr_linenumber" name="143" href="#143">143</a> <em class="jxr_javadoccomment"> * header from the frame.  If you don't want to strip the prepended header, you</em>
<a class="jxr_linenumber" name="144" href="#144">144</a> <em class="jxr_javadoccomment"> * could specify &lt;tt&gt;0&lt;/tt&gt; for &lt;tt&gt;initialBytesToSkip&lt;/tt&gt;.</em>
<a class="jxr_linenumber" name="145" href="#145">145</a> <em class="jxr_javadoccomment"> * &lt;pre&gt;</em>
<a class="jxr_linenumber" name="146" href="#146">146</a> <em class="jxr_javadoccomment"> * lengthFieldOffset   = 1 (= the length of HDR1)</em>
<a class="jxr_linenumber" name="147" href="#147">147</a> <em class="jxr_javadoccomment"> * lengthFieldLength   = 2</em>
<a class="jxr_linenumber" name="148" href="#148">148</a> <em class="jxr_javadoccomment"> * &lt;b&gt;lengthAdjustment&lt;/b&gt;    = &lt;b&gt;1&lt;/b&gt; (= the length of HDR2)</em>
<a class="jxr_linenumber" name="149" href="#149">149</a> <em class="jxr_javadoccomment"> * &lt;b&gt;initialBytesToStrip&lt;/b&gt; = &lt;b&gt;3&lt;/b&gt; (= the length of HDR1 + LEN)</em>
<a class="jxr_linenumber" name="150" href="#150">150</a> <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="151" href="#151">151</a> <em class="jxr_javadoccomment"> * BEFORE DECODE (16 bytes)                       AFTER DECODE (13 bytes)</em>
<a class="jxr_linenumber" name="152" href="#152">152</a> <em class="jxr_javadoccomment"> * +------+--------+------+----------------+      +------+----------------+</em>
<a class="jxr_linenumber" name="153" href="#153">153</a> <em class="jxr_javadoccomment"> * | HDR1 | Length | HDR2 | Actual Content |-----&gt;| HDR2 | Actual Content |</em>
<a class="jxr_linenumber" name="154" href="#154">154</a> <em class="jxr_javadoccomment"> * | 0xCA | 0x000C | 0xFE | "HELLO, WORLD" |      | 0xFE | "HELLO, WORLD" |</em>
<a class="jxr_linenumber" name="155" href="#155">155</a> <em class="jxr_javadoccomment"> * +------+--------+------+----------------+      +------+----------------+</em>
<a class="jxr_linenumber" name="156" href="#156">156</a> <em class="jxr_javadoccomment"> * &lt;/pre&gt;</em>
<a class="jxr_linenumber" name="157" href="#157">157</a> <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="158" href="#158">158</a> <em class="jxr_javadoccomment"> * &lt;h3&gt;2 bytes length field at offset 1 in the middle of 4 bytes header,</em>
<a class="jxr_linenumber" name="159" href="#159">159</a> <em class="jxr_javadoccomment"> *     strip the first header field and the length field, the length field</em>
<a class="jxr_linenumber" name="160" href="#160">160</a> <em class="jxr_javadoccomment"> *     represents the length of the whole message&lt;/h3&gt;</em>
<a class="jxr_linenumber" name="161" href="#161">161</a> <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="162" href="#162">162</a> <em class="jxr_javadoccomment"> * Let's give another twist to the previous example.  The only difference from</em>
<a class="jxr_linenumber" name="163" href="#163">163</a> <em class="jxr_javadoccomment"> * the previous example is that the length field represents the length of the</em>
<a class="jxr_linenumber" name="164" href="#164">164</a> <em class="jxr_javadoccomment"> * whole message instead of the message body, just like the third example.</em>
<a class="jxr_linenumber" name="165" href="#165">165</a> <em class="jxr_javadoccomment"> * We have to count the length of HDR1 and Length into &lt;tt&gt;lengthAdjustment&lt;/tt&gt;.</em>
<a class="jxr_linenumber" name="166" href="#166">166</a> <em class="jxr_javadoccomment"> * Please note that we don't need to take the length of HDR2 into account</em>
<a class="jxr_linenumber" name="167" href="#167">167</a> <em class="jxr_javadoccomment"> * because the length field already includes the whole header length.</em>
<a class="jxr_linenumber" name="168" href="#168">168</a> <em class="jxr_javadoccomment"> * &lt;pre&gt;</em>
<a class="jxr_linenumber" name="169" href="#169">169</a> <em class="jxr_javadoccomment"> * lengthFieldOffset   =  1</em>
<a class="jxr_linenumber" name="170" href="#170">170</a> <em class="jxr_javadoccomment"> * lengthFieldLength   =  2</em>
<a class="jxr_linenumber" name="171" href="#171">171</a> <em class="jxr_javadoccomment"> * &lt;b&gt;lengthAdjustment&lt;/b&gt;    = &lt;b&gt;-3&lt;/b&gt; (= the length of HDR1 + LEN, negative)</em>
<a class="jxr_linenumber" name="172" href="#172">172</a> <em class="jxr_javadoccomment"> * &lt;b&gt;initialBytesToStrip&lt;/b&gt; = &lt;b&gt; 3&lt;/b&gt;</em>
<a class="jxr_linenumber" name="173" href="#173">173</a> <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="174" href="#174">174</a> <em class="jxr_javadoccomment"> * BEFORE DECODE (16 bytes)                       AFTER DECODE (13 bytes)</em>
<a class="jxr_linenumber" name="175" href="#175">175</a> <em class="jxr_javadoccomment"> * +------+--------+------+----------------+      +------+----------------+</em>
<a class="jxr_linenumber" name="176" href="#176">176</a> <em class="jxr_javadoccomment"> * | HDR1 | Length | HDR2 | Actual Content |-----&gt;| HDR2 | Actual Content |</em>
<a class="jxr_linenumber" name="177" href="#177">177</a> <em class="jxr_javadoccomment"> * | 0xCA | 0x0010 | 0xFE | "HELLO, WORLD" |      | 0xFE | "HELLO, WORLD" |</em>
<a class="jxr_linenumber" name="178" href="#178">178</a> <em class="jxr_javadoccomment"> * +------+--------+------+----------------+      +------+----------------+</em>
<a class="jxr_linenumber" name="179" href="#179">179</a> <em class="jxr_javadoccomment"> * &lt;/pre&gt;</em>
<a class="jxr_linenumber" name="180" href="#180">180</a> <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="181" href="#181">181</a> <em class="jxr_javadoccomment"> * @see LengthFieldPrepender</em>
<a class="jxr_linenumber" name="182" href="#182">182</a> <em class="jxr_javadoccomment"> */</em>
<a class="jxr_linenumber" name="183" href="#183">183</a> <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">class</strong> <a href="../../../../../../org/jboss/netty/handler/codec/frame/LengthFieldBasedFrameDecoder.html">LengthFieldBasedFrameDecoder</a> <strong class="jxr_keyword">extends</strong> <a href="../../../../../../org/jboss/netty/handler/codec/frame/FrameDecoder.html">FrameDecoder</a> {
<a class="jxr_linenumber" name="184" href="#184">184</a> 
<a class="jxr_linenumber" name="185" href="#185">185</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">int</strong> maxFrameLength;
<a class="jxr_linenumber" name="186" href="#186">186</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">int</strong> lengthFieldOffset;
<a class="jxr_linenumber" name="187" href="#187">187</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">int</strong> lengthFieldLength;
<a class="jxr_linenumber" name="188" href="#188">188</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">int</strong> lengthFieldEndOffset;
<a class="jxr_linenumber" name="189" href="#189">189</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">int</strong> lengthAdjustment;
<a class="jxr_linenumber" name="190" href="#190">190</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">int</strong> initialBytesToStrip;
<a class="jxr_linenumber" name="191" href="#191">191</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">boolean</strong> failFast;
<a class="jxr_linenumber" name="192" href="#192">192</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">boolean</strong> discardingTooLongFrame;
<a class="jxr_linenumber" name="193" href="#193">193</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">long</strong> tooLongFrameLength;
<a class="jxr_linenumber" name="194" href="#194">194</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">long</strong> bytesToDiscard;
<a class="jxr_linenumber" name="195" href="#195">195</a> 
<a class="jxr_linenumber" name="196" href="#196">196</a>     <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="197" href="#197">197</a> <em class="jxr_javadoccomment">     * Creates a new instance.</em>
<a class="jxr_linenumber" name="198" href="#198">198</a> <em class="jxr_javadoccomment">     *</em>
<a class="jxr_linenumber" name="199" href="#199">199</a> <em class="jxr_javadoccomment">     * @param maxFrameLength</em>
<a class="jxr_linenumber" name="200" href="#200">200</a> <em class="jxr_javadoccomment">     *        the maximum length of the frame.  If the length of the frame is</em>
<a class="jxr_linenumber" name="201" href="#201">201</a> <em class="jxr_javadoccomment">     *        greater than this value, {@link TooLongFrameException} will be</em>
<a class="jxr_linenumber" name="202" href="#202">202</a> <em class="jxr_javadoccomment">     *        thrown.</em>
<a class="jxr_linenumber" name="203" href="#203">203</a> <em class="jxr_javadoccomment">     * @param lengthFieldOffset</em>
<a class="jxr_linenumber" name="204" href="#204">204</a> <em class="jxr_javadoccomment">     *        the offset of the length field</em>
<a class="jxr_linenumber" name="205" href="#205">205</a> <em class="jxr_javadoccomment">     * @param lengthFieldLength</em>
<a class="jxr_linenumber" name="206" href="#206">206</a> <em class="jxr_javadoccomment">     *        the length of the length field</em>
<a class="jxr_linenumber" name="207" href="#207">207</a> <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="208" href="#208">208</a>     <strong class="jxr_keyword">public</strong> <a href="../../../../../../org/jboss/netty/handler/codec/frame/LengthFieldBasedFrameDecoder.html">LengthFieldBasedFrameDecoder</a>(
<a class="jxr_linenumber" name="209" href="#209">209</a>             <strong class="jxr_keyword">int</strong> maxFrameLength,
<a class="jxr_linenumber" name="210" href="#210">210</a>             <strong class="jxr_keyword">int</strong> lengthFieldOffset, <strong class="jxr_keyword">int</strong> lengthFieldLength) {
<a class="jxr_linenumber" name="211" href="#211">211</a>         <strong class="jxr_keyword">this</strong>(maxFrameLength, lengthFieldOffset, lengthFieldLength, 0, 0);
<a class="jxr_linenumber" name="212" href="#212">212</a>     }
<a class="jxr_linenumber" name="213" href="#213">213</a> 
<a class="jxr_linenumber" name="214" href="#214">214</a>     <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="215" href="#215">215</a> <em class="jxr_javadoccomment">     * Creates a new instance.</em>
<a class="jxr_linenumber" name="216" href="#216">216</a> <em class="jxr_javadoccomment">     *</em>
<a class="jxr_linenumber" name="217" href="#217">217</a> <em class="jxr_javadoccomment">     * @param maxFrameLength</em>
<a class="jxr_linenumber" name="218" href="#218">218</a> <em class="jxr_javadoccomment">     *        the maximum length of the frame.  If the length of the frame is</em>
<a class="jxr_linenumber" name="219" href="#219">219</a> <em class="jxr_javadoccomment">     *        greater than this value, {@link TooLongFrameException} will be</em>
<a class="jxr_linenumber" name="220" href="#220">220</a> <em class="jxr_javadoccomment">     *        thrown.</em>
<a class="jxr_linenumber" name="221" href="#221">221</a> <em class="jxr_javadoccomment">     * @param lengthFieldOffset</em>
<a class="jxr_linenumber" name="222" href="#222">222</a> <em class="jxr_javadoccomment">     *        the offset of the length field</em>
<a class="jxr_linenumber" name="223" href="#223">223</a> <em class="jxr_javadoccomment">     * @param lengthFieldLength</em>
<a class="jxr_linenumber" name="224" href="#224">224</a> <em class="jxr_javadoccomment">     *        the length of the length field</em>
<a class="jxr_linenumber" name="225" href="#225">225</a> <em class="jxr_javadoccomment">     * @param lengthAdjustment</em>
<a class="jxr_linenumber" name="226" href="#226">226</a> <em class="jxr_javadoccomment">     *        the compensation value to add to the value of the length field</em>
<a class="jxr_linenumber" name="227" href="#227">227</a> <em class="jxr_javadoccomment">     * @param initialBytesToStrip</em>
<a class="jxr_linenumber" name="228" href="#228">228</a> <em class="jxr_javadoccomment">     *        the number of first bytes to strip out from the decoded frame</em>
<a class="jxr_linenumber" name="229" href="#229">229</a> <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="230" href="#230">230</a>     <strong class="jxr_keyword">public</strong> <a href="../../../../../../org/jboss/netty/handler/codec/frame/LengthFieldBasedFrameDecoder.html">LengthFieldBasedFrameDecoder</a>(
<a class="jxr_linenumber" name="231" href="#231">231</a>             <strong class="jxr_keyword">int</strong> maxFrameLength,
<a class="jxr_linenumber" name="232" href="#232">232</a>             <strong class="jxr_keyword">int</strong> lengthFieldOffset, <strong class="jxr_keyword">int</strong> lengthFieldLength,
<a class="jxr_linenumber" name="233" href="#233">233</a>             <strong class="jxr_keyword">int</strong> lengthAdjustment, <strong class="jxr_keyword">int</strong> initialBytesToStrip) {
<a class="jxr_linenumber" name="234" href="#234">234</a>         <strong class="jxr_keyword">this</strong>(
<a class="jxr_linenumber" name="235" href="#235">235</a>                 maxFrameLength,
<a class="jxr_linenumber" name="236" href="#236">236</a>                 lengthFieldOffset, lengthFieldLength, lengthAdjustment,
<a class="jxr_linenumber" name="237" href="#237">237</a>                 initialBytesToStrip, false);
<a class="jxr_linenumber" name="238" href="#238">238</a>     }
<a class="jxr_linenumber" name="239" href="#239">239</a> 
<a class="jxr_linenumber" name="240" href="#240">240</a>     <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="241" href="#241">241</a> <em class="jxr_javadoccomment">     * Creates a new instance.</em>
<a class="jxr_linenumber" name="242" href="#242">242</a> <em class="jxr_javadoccomment">     *</em>
<a class="jxr_linenumber" name="243" href="#243">243</a> <em class="jxr_javadoccomment">     * @param maxFrameLength</em>
<a class="jxr_linenumber" name="244" href="#244">244</a> <em class="jxr_javadoccomment">     *        the maximum length of the frame.  If the length of the frame is</em>
<a class="jxr_linenumber" name="245" href="#245">245</a> <em class="jxr_javadoccomment">     *        greater than this value, {@link TooLongFrameException} will be</em>
<a class="jxr_linenumber" name="246" href="#246">246</a> <em class="jxr_javadoccomment">     *        thrown.</em>
<a class="jxr_linenumber" name="247" href="#247">247</a> <em class="jxr_javadoccomment">     * @param lengthFieldOffset</em>
<a class="jxr_linenumber" name="248" href="#248">248</a> <em class="jxr_javadoccomment">     *        the offset of the length field</em>
<a class="jxr_linenumber" name="249" href="#249">249</a> <em class="jxr_javadoccomment">     * @param lengthFieldLength</em>
<a class="jxr_linenumber" name="250" href="#250">250</a> <em class="jxr_javadoccomment">     *        the length of the length field</em>
<a class="jxr_linenumber" name="251" href="#251">251</a> <em class="jxr_javadoccomment">     * @param lengthAdjustment</em>
<a class="jxr_linenumber" name="252" href="#252">252</a> <em class="jxr_javadoccomment">     *        the compensation value to add to the value of the length field</em>
<a class="jxr_linenumber" name="253" href="#253">253</a> <em class="jxr_javadoccomment">     * @param initialBytesToStrip</em>
<a class="jxr_linenumber" name="254" href="#254">254</a> <em class="jxr_javadoccomment">     *        the number of first bytes to strip out from the decoded frame</em>
<a class="jxr_linenumber" name="255" href="#255">255</a> <em class="jxr_javadoccomment">     * @param failFast</em>
<a class="jxr_linenumber" name="256" href="#256">256</a> <em class="jxr_javadoccomment">     *        If &lt;tt&gt;true&lt;/tt&gt;, a {@link TooLongFrameException} is thrown as</em>
<a class="jxr_linenumber" name="257" href="#257">257</a> <em class="jxr_javadoccomment">     *        soon as the decoder notices the length of the frame will exceed</em>
<a class="jxr_linenumber" name="258" href="#258">258</a> <em class="jxr_javadoccomment">     *        &lt;tt&gt;maxFrameLength&lt;/tt&gt; regardless of whether the entire frame</em>
<a class="jxr_linenumber" name="259" href="#259">259</a> <em class="jxr_javadoccomment">     *        has been read.  If &lt;tt&gt;false&lt;/tt&gt;, a {@link TooLongFrameException}</em>
<a class="jxr_linenumber" name="260" href="#260">260</a> <em class="jxr_javadoccomment">     *        is thrown after the entire frame that exceeds &lt;tt&gt;maxFrameLength&lt;/tt&gt;</em>
<a class="jxr_linenumber" name="261" href="#261">261</a> <em class="jxr_javadoccomment">     *        has been read.</em>
<a class="jxr_linenumber" name="262" href="#262">262</a> <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="263" href="#263">263</a>     <strong class="jxr_keyword">public</strong> <a href="../../../../../../org/jboss/netty/handler/codec/frame/LengthFieldBasedFrameDecoder.html">LengthFieldBasedFrameDecoder</a>(
<a class="jxr_linenumber" name="264" href="#264">264</a>             <strong class="jxr_keyword">int</strong> maxFrameLength,
<a class="jxr_linenumber" name="265" href="#265">265</a>             <strong class="jxr_keyword">int</strong> lengthFieldOffset, <strong class="jxr_keyword">int</strong> lengthFieldLength,
<a class="jxr_linenumber" name="266" href="#266">266</a>             <strong class="jxr_keyword">int</strong> lengthAdjustment, <strong class="jxr_keyword">int</strong> initialBytesToStrip, <strong class="jxr_keyword">boolean</strong> failFast) {
<a class="jxr_linenumber" name="267" href="#267">267</a>         <strong class="jxr_keyword">if</strong> (maxFrameLength &lt;= 0) {
<a class="jxr_linenumber" name="268" href="#268">268</a>             <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> IllegalArgumentException(
<a class="jxr_linenumber" name="269" href="#269">269</a>                     <span class="jxr_string">"maxFrameLength must be a positive integer: "</span> +
<a class="jxr_linenumber" name="270" href="#270">270</a>                     maxFrameLength);
<a class="jxr_linenumber" name="271" href="#271">271</a>         }
<a class="jxr_linenumber" name="272" href="#272">272</a> 
<a class="jxr_linenumber" name="273" href="#273">273</a>         <strong class="jxr_keyword">if</strong> (lengthFieldOffset &lt; 0) {
<a class="jxr_linenumber" name="274" href="#274">274</a>             <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> IllegalArgumentException(
<a class="jxr_linenumber" name="275" href="#275">275</a>                     <span class="jxr_string">"lengthFieldOffset must be a non-negative integer: "</span> +
<a class="jxr_linenumber" name="276" href="#276">276</a>                     lengthFieldOffset);
<a class="jxr_linenumber" name="277" href="#277">277</a>         }
<a class="jxr_linenumber" name="278" href="#278">278</a> 
<a class="jxr_linenumber" name="279" href="#279">279</a>         <strong class="jxr_keyword">if</strong> (initialBytesToStrip &lt; 0) {
<a class="jxr_linenumber" name="280" href="#280">280</a>             <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> IllegalArgumentException(
<a class="jxr_linenumber" name="281" href="#281">281</a>                     <span class="jxr_string">"initialBytesToStrip must be a non-negative integer: "</span> +
<a class="jxr_linenumber" name="282" href="#282">282</a>                     initialBytesToStrip);
<a class="jxr_linenumber" name="283" href="#283">283</a>         }
<a class="jxr_linenumber" name="284" href="#284">284</a> 
<a class="jxr_linenumber" name="285" href="#285">285</a>         <strong class="jxr_keyword">if</strong> (lengthFieldLength != 1 &amp;&amp; lengthFieldLength != 2 &amp;&amp;
<a class="jxr_linenumber" name="286" href="#286">286</a>             lengthFieldLength != 3 &amp;&amp; lengthFieldLength != 4 &amp;&amp;
<a class="jxr_linenumber" name="287" href="#287">287</a>             lengthFieldLength != 8) {
<a class="jxr_linenumber" name="288" href="#288">288</a>             <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> IllegalArgumentException(
<a class="jxr_linenumber" name="289" href="#289">289</a>                     <span class="jxr_string">"lengthFieldLength must be either 1, 2, 3, 4, or 8: "</span> +
<a class="jxr_linenumber" name="290" href="#290">290</a>                     lengthFieldLength);
<a class="jxr_linenumber" name="291" href="#291">291</a>         }
<a class="jxr_linenumber" name="292" href="#292">292</a> 
<a class="jxr_linenumber" name="293" href="#293">293</a>         <strong class="jxr_keyword">if</strong> (lengthFieldOffset &gt; maxFrameLength - lengthFieldLength) {
<a class="jxr_linenumber" name="294" href="#294">294</a>             <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> IllegalArgumentException(
<a class="jxr_linenumber" name="295" href="#295">295</a>                     <span class="jxr_string">"maxFrameLength ("</span> + maxFrameLength + <span class="jxr_string">") "</span> +
<a class="jxr_linenumber" name="296" href="#296">296</a>                     <span class="jxr_string">"must be equal to or greater than "</span> +
<a class="jxr_linenumber" name="297" href="#297">297</a>                     <span class="jxr_string">"lengthFieldOffset ("</span> + lengthFieldOffset + <span class="jxr_string">") + "</span> +
<a class="jxr_linenumber" name="298" href="#298">298</a>                     <span class="jxr_string">"lengthFieldLength ("</span> + lengthFieldLength + <span class="jxr_string">")."</span>);
<a class="jxr_linenumber" name="299" href="#299">299</a>         }
<a class="jxr_linenumber" name="300" href="#300">300</a> 
<a class="jxr_linenumber" name="301" href="#301">301</a>         <strong class="jxr_keyword">this</strong>.maxFrameLength = maxFrameLength;
<a class="jxr_linenumber" name="302" href="#302">302</a>         <strong class="jxr_keyword">this</strong>.lengthFieldOffset = lengthFieldOffset;
<a class="jxr_linenumber" name="303" href="#303">303</a>         <strong class="jxr_keyword">this</strong>.lengthFieldLength = lengthFieldLength;
<a class="jxr_linenumber" name="304" href="#304">304</a>         <strong class="jxr_keyword">this</strong>.lengthAdjustment = lengthAdjustment;
<a class="jxr_linenumber" name="305" href="#305">305</a>         lengthFieldEndOffset = lengthFieldOffset + lengthFieldLength;
<a class="jxr_linenumber" name="306" href="#306">306</a>         <strong class="jxr_keyword">this</strong>.initialBytesToStrip = initialBytesToStrip;
<a class="jxr_linenumber" name="307" href="#307">307</a>         <strong class="jxr_keyword">this</strong>.failFast = failFast;
<a class="jxr_linenumber" name="308" href="#308">308</a>     }
<a class="jxr_linenumber" name="309" href="#309">309</a> 
<a class="jxr_linenumber" name="310" href="#310">310</a>     @Override
<a class="jxr_linenumber" name="311" href="#311">311</a>     <strong class="jxr_keyword">protected</strong> Object decode(
<a class="jxr_linenumber" name="312" href="#312">312</a>             <a href="../../../../../../org/jboss/netty/channel/ChannelHandlerContext.html">ChannelHandlerContext</a> ctx, <a href="../../../../../../org/jboss/netty/channel/Channel.html">Channel</a> channel, <a href="../../../../../../org/jboss/netty/buffer/ChannelBuffer.html">ChannelBuffer</a> buffer) <strong class="jxr_keyword">throws</strong> Exception {
<a class="jxr_linenumber" name="313" href="#313">313</a> 
<a class="jxr_linenumber" name="314" href="#314">314</a>         <strong class="jxr_keyword">if</strong> (discardingTooLongFrame) {
<a class="jxr_linenumber" name="315" href="#315">315</a>             <strong class="jxr_keyword">long</strong> bytesToDiscard = <strong class="jxr_keyword">this</strong>.bytesToDiscard;
<a class="jxr_linenumber" name="316" href="#316">316</a>             <strong class="jxr_keyword">int</strong> localBytesToDiscard = (<strong class="jxr_keyword">int</strong>) Math.min(bytesToDiscard, buffer.readableBytes());
<a class="jxr_linenumber" name="317" href="#317">317</a>             buffer.skipBytes(localBytesToDiscard);
<a class="jxr_linenumber" name="318" href="#318">318</a>             bytesToDiscard -= localBytesToDiscard;
<a class="jxr_linenumber" name="319" href="#319">319</a>             <strong class="jxr_keyword">this</strong>.bytesToDiscard = bytesToDiscard;
<a class="jxr_linenumber" name="320" href="#320">320</a>             failIfNecessary(ctx, false);
<a class="jxr_linenumber" name="321" href="#321">321</a>             <strong class="jxr_keyword">return</strong> <strong class="jxr_keyword">null</strong>;
<a class="jxr_linenumber" name="322" href="#322">322</a>         }
<a class="jxr_linenumber" name="323" href="#323">323</a> 
<a class="jxr_linenumber" name="324" href="#324">324</a>         <strong class="jxr_keyword">if</strong> (buffer.readableBytes() &lt; lengthFieldEndOffset) {
<a class="jxr_linenumber" name="325" href="#325">325</a>             <strong class="jxr_keyword">return</strong> <strong class="jxr_keyword">null</strong>;
<a class="jxr_linenumber" name="326" href="#326">326</a>         }
<a class="jxr_linenumber" name="327" href="#327">327</a> 
<a class="jxr_linenumber" name="328" href="#328">328</a>         <strong class="jxr_keyword">int</strong> actualLengthFieldOffset = buffer.readerIndex() + lengthFieldOffset;
<a class="jxr_linenumber" name="329" href="#329">329</a>         <strong class="jxr_keyword">long</strong> frameLength;
<a class="jxr_linenumber" name="330" href="#330">330</a>         <strong class="jxr_keyword">switch</strong> (lengthFieldLength) {
<a class="jxr_linenumber" name="331" href="#331">331</a>         <strong class="jxr_keyword">case</strong> 1:
<a class="jxr_linenumber" name="332" href="#332">332</a>             frameLength = buffer.getUnsignedByte(actualLengthFieldOffset);
<a class="jxr_linenumber" name="333" href="#333">333</a>             <strong class="jxr_keyword">break</strong>;
<a class="jxr_linenumber" name="334" href="#334">334</a>         <strong class="jxr_keyword">case</strong> 2:
<a class="jxr_linenumber" name="335" href="#335">335</a>             frameLength = buffer.getUnsignedShort(actualLengthFieldOffset);
<a class="jxr_linenumber" name="336" href="#336">336</a>             <strong class="jxr_keyword">break</strong>;
<a class="jxr_linenumber" name="337" href="#337">337</a>         <strong class="jxr_keyword">case</strong> 3:
<a class="jxr_linenumber" name="338" href="#338">338</a>             frameLength = buffer.getUnsignedMedium(actualLengthFieldOffset);
<a class="jxr_linenumber" name="339" href="#339">339</a>             <strong class="jxr_keyword">break</strong>;
<a class="jxr_linenumber" name="340" href="#340">340</a>         <strong class="jxr_keyword">case</strong> 4:
<a class="jxr_linenumber" name="341" href="#341">341</a>             frameLength = buffer.getUnsignedInt(actualLengthFieldOffset);
<a class="jxr_linenumber" name="342" href="#342">342</a>             <strong class="jxr_keyword">break</strong>;
<a class="jxr_linenumber" name="343" href="#343">343</a>         <strong class="jxr_keyword">case</strong> 8:
<a class="jxr_linenumber" name="344" href="#344">344</a>             frameLength = buffer.getLong(actualLengthFieldOffset);
<a class="jxr_linenumber" name="345" href="#345">345</a>             <strong class="jxr_keyword">break</strong>;
<a class="jxr_linenumber" name="346" href="#346">346</a>         <strong class="jxr_keyword">default</strong>:
<a class="jxr_linenumber" name="347" href="#347">347</a>             <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> Error(<span class="jxr_string">"should not reach here"</span>);
<a class="jxr_linenumber" name="348" href="#348">348</a>         }
<a class="jxr_linenumber" name="349" href="#349">349</a> 
<a class="jxr_linenumber" name="350" href="#350">350</a>         <strong class="jxr_keyword">if</strong> (frameLength &lt; 0) {
<a class="jxr_linenumber" name="351" href="#351">351</a>             buffer.skipBytes(lengthFieldEndOffset);
<a class="jxr_linenumber" name="352" href="#352">352</a>             <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> <a href="../../../../../../org/jboss/netty/handler/codec/frame/CorruptedFrameException.html">CorruptedFrameException</a>(
<a class="jxr_linenumber" name="353" href="#353">353</a>                     <span class="jxr_string">"negative pre-adjustment length field: "</span> + frameLength);
<a class="jxr_linenumber" name="354" href="#354">354</a>         }
<a class="jxr_linenumber" name="355" href="#355">355</a> 
<a class="jxr_linenumber" name="356" href="#356">356</a>         frameLength += lengthAdjustment + lengthFieldEndOffset;
<a class="jxr_linenumber" name="357" href="#357">357</a>         <strong class="jxr_keyword">if</strong> (frameLength &lt; lengthFieldEndOffset) {
<a class="jxr_linenumber" name="358" href="#358">358</a>             buffer.skipBytes(lengthFieldEndOffset);
<a class="jxr_linenumber" name="359" href="#359">359</a>             <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> <a href="../../../../../../org/jboss/netty/handler/codec/frame/CorruptedFrameException.html">CorruptedFrameException</a>(
<a class="jxr_linenumber" name="360" href="#360">360</a>                     <span class="jxr_string">"Adjusted frame length ("</span> + frameLength + <span class="jxr_string">") is less "</span> +
<a class="jxr_linenumber" name="361" href="#361">361</a>                     <span class="jxr_string">"than lengthFieldEndOffset: "</span> + lengthFieldEndOffset);
<a class="jxr_linenumber" name="362" href="#362">362</a>         }
<a class="jxr_linenumber" name="363" href="#363">363</a> 
<a class="jxr_linenumber" name="364" href="#364">364</a>         <strong class="jxr_keyword">if</strong> (frameLength &gt; maxFrameLength) {
<a class="jxr_linenumber" name="365" href="#365">365</a>             <em class="jxr_comment">// Enter the discard mode and discard everything received so far.</em>
<a class="jxr_linenumber" name="366" href="#366">366</a>             discardingTooLongFrame = <strong class="jxr_keyword">true</strong>;
<a class="jxr_linenumber" name="367" href="#367">367</a>             tooLongFrameLength = frameLength;
<a class="jxr_linenumber" name="368" href="#368">368</a>             bytesToDiscard = frameLength - buffer.readableBytes();
<a class="jxr_linenumber" name="369" href="#369">369</a>             buffer.skipBytes(buffer.readableBytes());
<a class="jxr_linenumber" name="370" href="#370">370</a>             failIfNecessary(ctx, <strong class="jxr_keyword">true</strong>);
<a class="jxr_linenumber" name="371" href="#371">371</a>             <strong class="jxr_keyword">return</strong> <strong class="jxr_keyword">null</strong>;
<a class="jxr_linenumber" name="372" href="#372">372</a>         }
<a class="jxr_linenumber" name="373" href="#373">373</a> 
<a class="jxr_linenumber" name="374" href="#374">374</a>         <em class="jxr_comment">// never overflows because it's less than maxFrameLength</em>
<a class="jxr_linenumber" name="375" href="#375">375</a>         <strong class="jxr_keyword">int</strong> frameLengthInt = (<strong class="jxr_keyword">int</strong>) frameLength;
<a class="jxr_linenumber" name="376" href="#376">376</a>         <strong class="jxr_keyword">if</strong> (buffer.readableBytes() &lt; frameLengthInt) {
<a class="jxr_linenumber" name="377" href="#377">377</a>             <strong class="jxr_keyword">return</strong> <strong class="jxr_keyword">null</strong>;
<a class="jxr_linenumber" name="378" href="#378">378</a>         }
<a class="jxr_linenumber" name="379" href="#379">379</a> 
<a class="jxr_linenumber" name="380" href="#380">380</a>         <strong class="jxr_keyword">if</strong> (initialBytesToStrip &gt; frameLengthInt) {
<a class="jxr_linenumber" name="381" href="#381">381</a>             buffer.skipBytes(frameLengthInt);
<a class="jxr_linenumber" name="382" href="#382">382</a>             <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> <a href="../../../../../../org/jboss/netty/handler/codec/frame/CorruptedFrameException.html">CorruptedFrameException</a>(
<a class="jxr_linenumber" name="383" href="#383">383</a>                     <span class="jxr_string">"Adjusted frame length ("</span> + frameLength + <span class="jxr_string">") is less "</span> +
<a class="jxr_linenumber" name="384" href="#384">384</a>                     <span class="jxr_string">"than initialBytesToStrip: "</span> + initialBytesToStrip);
<a class="jxr_linenumber" name="385" href="#385">385</a>         }
<a class="jxr_linenumber" name="386" href="#386">386</a>         buffer.skipBytes(initialBytesToStrip);
<a class="jxr_linenumber" name="387" href="#387">387</a> 
<a class="jxr_linenumber" name="388" href="#388">388</a>         <em class="jxr_comment">// extract frame</em>
<a class="jxr_linenumber" name="389" href="#389">389</a>         <strong class="jxr_keyword">int</strong> readerIndex = buffer.readerIndex();
<a class="jxr_linenumber" name="390" href="#390">390</a>         <strong class="jxr_keyword">int</strong> actualFrameLength = frameLengthInt - initialBytesToStrip;
<a class="jxr_linenumber" name="391" href="#391">391</a>         <a href="../../../../../../org/jboss/netty/buffer/ChannelBuffer.html">ChannelBuffer</a> frame = extractFrame(buffer, readerIndex, actualFrameLength);
<a class="jxr_linenumber" name="392" href="#392">392</a>         buffer.readerIndex(readerIndex + actualFrameLength);
<a class="jxr_linenumber" name="393" href="#393">393</a>         <strong class="jxr_keyword">return</strong> frame;
<a class="jxr_linenumber" name="394" href="#394">394</a>     }
<a class="jxr_linenumber" name="395" href="#395">395</a> 
<a class="jxr_linenumber" name="396" href="#396">396</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">void</strong> failIfNecessary(<a href="../../../../../../org/jboss/netty/channel/ChannelHandlerContext.html">ChannelHandlerContext</a> ctx, <strong class="jxr_keyword">boolean</strong> firstDetectionOfTooLongFrame) {
<a class="jxr_linenumber" name="397" href="#397">397</a>         <strong class="jxr_keyword">if</strong> (bytesToDiscard == 0) {
<a class="jxr_linenumber" name="398" href="#398">398</a>             <em class="jxr_comment">// Reset to the initial state and tell the handlers that</em>
<a class="jxr_linenumber" name="399" href="#399">399</a>             <em class="jxr_comment">// the frame was too large.</em>
<a class="jxr_linenumber" name="400" href="#400">400</a>             <strong class="jxr_keyword">long</strong> tooLongFrameLength = <strong class="jxr_keyword">this</strong>.tooLongFrameLength;
<a class="jxr_linenumber" name="401" href="#401">401</a>             <strong class="jxr_keyword">this</strong>.tooLongFrameLength = 0;
<a class="jxr_linenumber" name="402" href="#402">402</a>             discardingTooLongFrame = false;
<a class="jxr_linenumber" name="403" href="#403">403</a>             <strong class="jxr_keyword">if</strong> (!failFast ||
<a class="jxr_linenumber" name="404" href="#404">404</a>                 failFast &amp;&amp; firstDetectionOfTooLongFrame) {
<a class="jxr_linenumber" name="405" href="#405">405</a>                 fail(ctx, tooLongFrameLength);
<a class="jxr_linenumber" name="406" href="#406">406</a>             }
<a class="jxr_linenumber" name="407" href="#407">407</a>         } <strong class="jxr_keyword">else</strong> {
<a class="jxr_linenumber" name="408" href="#408">408</a>             <em class="jxr_comment">// Keep discarding and notify handlers if necessary.</em>
<a class="jxr_linenumber" name="409" href="#409">409</a>             <strong class="jxr_keyword">if</strong> (failFast &amp;&amp; firstDetectionOfTooLongFrame) {
<a class="jxr_linenumber" name="410" href="#410">410</a>                 fail(ctx, tooLongFrameLength);
<a class="jxr_linenumber" name="411" href="#411">411</a>             }
<a class="jxr_linenumber" name="412" href="#412">412</a>         }
<a class="jxr_linenumber" name="413" href="#413">413</a>     }
<a class="jxr_linenumber" name="414" href="#414">414</a> 
<a class="jxr_linenumber" name="415" href="#415">415</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">void</strong> fail(<a href="../../../../../../org/jboss/netty/channel/ChannelHandlerContext.html">ChannelHandlerContext</a> ctx, <strong class="jxr_keyword">long</strong> frameLength) {
<a class="jxr_linenumber" name="416" href="#416">416</a>         <strong class="jxr_keyword">if</strong> (frameLength &gt; 0) {
<a class="jxr_linenumber" name="417" href="#417">417</a>             Channels.fireExceptionCaught(
<a class="jxr_linenumber" name="418" href="#418">418</a>                     ctx.getChannel(),
<a class="jxr_linenumber" name="419" href="#419">419</a>                     <strong class="jxr_keyword">new</strong> <a href="../../../../../../org/jboss/netty/handler/codec/frame/TooLongFrameException.html">TooLongFrameException</a>(
<a class="jxr_linenumber" name="420" href="#420">420</a>                             <span class="jxr_string">"Adjusted frame length exceeds "</span> + maxFrameLength +
<a class="jxr_linenumber" name="421" href="#421">421</a>                             <span class="jxr_string">": "</span> + frameLength + <span class="jxr_string">" - discarded"</span>));
<a class="jxr_linenumber" name="422" href="#422">422</a>         } <strong class="jxr_keyword">else</strong> {
<a class="jxr_linenumber" name="423" href="#423">423</a>             Channels.fireExceptionCaught(
<a class="jxr_linenumber" name="424" href="#424">424</a>                     ctx.getChannel(),
<a class="jxr_linenumber" name="425" href="#425">425</a>                     <strong class="jxr_keyword">new</strong> <a href="../../../../../../org/jboss/netty/handler/codec/frame/TooLongFrameException.html">TooLongFrameException</a>(
<a class="jxr_linenumber" name="426" href="#426">426</a>                             <span class="jxr_string">"Adjusted frame length exceeds "</span> + maxFrameLength +
<a class="jxr_linenumber" name="427" href="#427">427</a>                             <span class="jxr_string">" - discarding"</span>));
<a class="jxr_linenumber" name="428" href="#428">428</a>         }
<a class="jxr_linenumber" name="429" href="#429">429</a>     }
<a class="jxr_linenumber" name="430" href="#430">430</a> }
</pre>
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